Optical fiber connection

ABSTRACT

Optical fiber connections and their applications in downhole assemblies are described herein. The downhole assembly includes a well completion element with an end that couples with a corresponding well completion element. An optical fiber extends along at least a portion of the well completion element and transmits an optical signal using a first mode. The well completion element includes an optical fiber connector that is coupled to the optical fiber. The connector also includes a mode converter that receives the optical signal from the optical fiber and converts the optical signal from the first mode to a second larger mode. This second larger mode may be more robustly communicated to a corresponding optical fiber connector affixed to the corresponding well completion element.

CROSS REFERENCE PARAGRAPH

This application is a continuation of U.S. application Ser. No.15/532,870, filed Jun. 2, 2017, which is a National Stage Entry ofInternational Application PCT/US2015/063445, filed Dec. 2, 2015, whichclaims Priority to U.S. Application Ser. No. 62/086,539 filed Dec. 2,2014, which applications are incorporated herein, in their entirety, byreference.

BACKGROUND

Fiber optic sensors are currently used in a wide variety of industries,including those where remote sensing of temperature, strain, pressureand other quantities is desired. Since fiber optic sensors can employoptical fibers as a sensing element, they can be immune from electricalinterference, small in size, and can operate in high heat environments.

This combination of performance characteristics allows fiber opticsensors to be used in environments where other sensors are impracticaland/or suffer from performance issues. For example, fiber optic sensorscan be used in a variety of oilfield services applications, including indownhole environments too hot for semiconductor sensing technologies.

SUMMARY

Illustrative embodiments of the present disclosure are directed tooptical fiber connections and their applications in downhole assemblies.In various embodiments, the downhole assembly includes a well completionelement with an end that couples with a corresponding well completionelement. An optical fiber extends along at least a portion of the wellcompletion element and transmits an optical signal using a first mode.The well completion element includes an optical fiber connector that iscoupled to the optical fiber. The connector also includes a modeconverter that receives the optical signal from the optical fiber andconverts the optical signal from the first mode to a second larger mode.This second larger mode may be used to more robustly communicate theoptical signal to a corresponding optical fiber connector affixed to thecorresponding well completion element.

In some embodiments, the mode converter transmits the optical signal toa second optical fiber that transmits the optical signal using thesecond larger mode. In further illustrative embodiments, the core of thesecond optical fiber is larger than the core the optical fiber. Thelarger core may be used to more robustly communicate the optical signalto a corresponding optical fiber connector affixed to the correspondingwell completion element.

Various embodiments of the present disclosure are also directed to anoptical fiber connector. The optical fiber connector includes an opticalfiber that transmits an optical signal using a first mode. The opticalfiber connector further includes a mode converter that receives theoptical signal from the optical fiber and converts the optical signalfrom a first mode to a second larger mode. This second larger mode maybe used to more robustly communicate the optical signal to acorresponding optical fiber connector. The mode converter and at least aportion of the optical fiber are a single solid component.

In some embodiments, the optical fiber connector also includes a secondoptical fiber that transmits the optical signal using the second largermode. The mode converter transmits the optical signal to the secondoptical fiber. In further illustrative embodiments, the core of thesecond optical fiber is larger than the core the optical fiber. Thelarger core may be used to more robustly communicate the optical signalto a corresponding optical fiber connector.

This summary is not intended to identify key or essential features ofthe claimed subject matter, nor is it intended to be used as an aid inlimiting the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the described implementations can be morereadily understood by reference to the following description taken inconjunction with the accompanying drawings.

FIG. 1A shows an example downhole assembly with an upper element and alower element in an uncoupled state in accordance with one embodiment ofthe present disclosure;

FIG. 1B shows the example downhole assembly of FIG. 1B in a coupledstate;

FIG. 2 shows an example latch coupling an upper element and a lowerelement of a downhole assembly in accordance with one embodiment of thepresent disclosure;

FIG. 3 shows an example mode converter design in accordance with oneembodiment of the present disclosure;

FIG. 4 shows another mode converter design in accordance with oneembodiment of the present disclosure;

FIG. 5 shows another mode converter design in accordance with oneembodiment of the present disclosure;

FIG. 6 shows another mode converter design incorporating lenses inaccordance with one embodiment of the present disclosure;

FIG. 7A shows male and female optical fiber connectors in a disconnectedstate in accordance with one embodiment of the present disclosure;

FIG. 7B shows the male and female optical fiber connectors of FIG. 7A ina connected state;

FIG. 8A shows a connector design that uses a beam forming grating inaccordance with one embodiment of the present disclosure;

FIG. 8B shows a connector design that uses a curved beam forming gratingin accordance with one embodiment of the present disclosure;

FIG. 9 shows a connector design that uses a resonant beam forminggrating in accordance with one embodiment of the present disclosure;

FIG. 10 shows an example method in accordance with one embodiment of thepresent disclosure; and

FIG. 11 shows an example computing environment that can be used inaccordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

Illustrative embodiments of the present disclosure are directed totechniques and technologies that facilitate connection between opticalfibers. For example, in one possible implementation, a connectionbetween two optical fibers can be facilitated by converting an opticalsignal within an optical fiber from a first mode to a second larger modethrough use of one or more mode converters.

As used herein, the term “optical fiber” includes any fiber capable ofconveying an optical signal, including single mode fibers, multimodefibers, ribbon fibers, fibers that include fiber bragg gratings,multi-core fibers, photonic-crystal fibers (PCF), Siamese fibers, etc.

Optical signals can include any optical information in analog or digitalform (including data, measurements, etc.), power to be transmittedoptically, etc. In one possible implementation, optical signals caninclude any wavelengths and frequencies known in the art and can conveyany spectral information known in the art, including for exampleRayleigh information, Raman information, Coherent information, etc.Moreover, any techniques known in the art can be used to transmit,receive, and/or process the optical signals, including for example anyphoton counting techniques known in the art.

In one possible implementation, the optical fiber connection can be usedto create and employ optical fiber sensing technologies to replaceand/or augment electrical sensors and collect information regardingvarious aspects of a well (including a completed well), such as forexample, temperature, pressure, strain, vibration, chemical composition,gas composition, etc. Additionally, fiber optic technology (e.g.,optical fibers and the connections described herein) can be used toreplace electrical cables.

Example Equipment

FIG. 1A shows an example downhole assembly 100 that uses optical fibersand optical fiber connectors. Downhole assembly 100 can include anydownhole equipment used in the art, including, for example, equipmentassociated with operations such as completions, artificial lift, slickline, wireline, etc. Moreover, downhole assembly 100 can be employed inany environment found in oilfield services, such as, for example, dry orwet environments including hydrocarbons, water, gas, etc.

For the sake of illustration, and not limitation, downhole assembly 100in FIG. 1A is shown as completions equipment having an upper element 102(such as an upper completions element) and a lower element 104 (such asa lower completions element) in a well 106. Lower element 104 cancontact a casing 108 of well 106 that traverses a formation 105 (suchas, for example through one or more packers 110), while also extendinginto an unfinished, open hole section 112 of the well 106.

In one possible implementation, lower element 104 can be placed in well106 before upper element 102. For example, in the case of completionsequipment, lower element 104 can be placed in well 106 and left in placefor up to several years while other wells proximate to well 106 (suchas, for example, injector wells) are drilled. After these other wellsare in place, upper element 102 can be placed downhole in well 106 tointeract with lower element 104 in any way known in the art.

In one possible implementation, such interaction can include physicalcoupling of upper element 102 to lower element 104. For example, in onepossible aspect, a terminal end 114 of upper element 102 can be placedinside a receiving end 116 of lower element 104. In the case of downholeassembly 100, this can place a male inductive coupler 118 on upperelement 102 proximate a female inductive coupler 120 on lower element104, functionally coupling male inductive coupler 118 and femaleinductive coupler 120. One or more packers 122 can also be included onupper element 102 to help facilitate various activities, such asproduction, in the well 106.

In one possible implementation, various sensors 124, including opticalfiber sensors, can be placed on or proximate to lower element 104.Communication from sensors 124 can occur via an optical fiber 126 thatextends along a length of lower element 104. The optical fiber 126 canbe functionally coupled with an optical fiber 128 that extends along alength of upper element 102. Functional coupling, as will be describedin greater detail below, can be accomplished using fiber opticconnectors (including contact and contactless connections of opticalfibers 126, 128). Moreover, more than one set of optical fibers 126, 128can be found on downhole assembly 100. Optical fibers 126, 128 can beconstructed of any materials known in the art, including, for example,glass, fluoride, etc.

In one possible embodiment, optical fibers 126, 128 can support guidedmodes. Moreover, depending on the diameter and geometry of the opticalfibers 126, 128, the optical fibers 126, 128 may be able to transportsingle and/or multiple modes. Some or all of the modes can be preservedwhen optical fibers 126, 128 are coupled.

In one possible embodiment, the various sensors 124 can receive a widevariety of information regarding downhole assembly 100, well 106, andthe formation that surrounds the well. In one possible aspect, sensors124 can take measurements when activities take place, such as productionof fluids from the formation into well 106.

In one possible embodiment, sensors 124 can be employed as any optical,electrical and/or magnetic distributed sensing technologies known in theart. For example, sensors 124 can provide distributed measurements andsensors 124 can be associated with point sensing, array sensing and/orquasi array sensing.

Sensors 124 can include, for example, distributed strain sensors,distributed acoustic/vibration sensors for acoustic/vibrationmonitoring, distributed chemical sensors, point sensors for pressure,temperature, strain, vibration, etc. In one possible aspect,measurements from sensors 124 can be used to understand variousparameters including, for example, reservoir connectivity, drainage, andflow assurance. Such information can potentially give an operator theability to extend the life of well 106 and avoid potentially expensiveinterventions through better understanding of various parameters suchas, for example, production logging, flow rate, flow allocation,integrity monitoring, gas lift, vertical seismic profiling, leakdetection, fluid level indication, structural and mechanical detailsassociated with both reservoir and well completion components, fluidphase information in single/two/three phases, plug and abandonmentinformation, compaction monitoring, sand detection, proppant andfracture monitoring, micro seismic information, etc.

In addition to conveying optical signals comprising measurements anddata between upper element 102 and lower element 104, in one possibleembodiment, optical fibers 126, 128 can allow for transmission of powerbetween upper element 102 and lower element 104 through the conveyanceof optical signals.

FIG. 1B illustrates an example coupling of upper element 102 and lowerelement 104. As illustrated, terminal end 114 of upper element 102 isinside receiving end 116 of lower element 104. In one possibleimplementation, when upper element 102 is coupled to lower element 104,optical fiber 126 is functionally coupled to optical fiber 128 usingoptical fiber connectors 129 and 131. Optical fiber connector 129 isrigidly attached to the upper completion 102 and is also coupled tooptical fiber 128. Optical fiber connector 131 is rigidly attached tothe lower completion 104 and is also coupled to optical fiber 126. FIG.1A shows the optical fiber connectors 129 and 131 when they aredisconnected and FIG. 1B shows the connectors when they are connected.In one possible embodiment, optical fiber 128 can be functionallycoupled to optical fiber 126 inside of an element on lower element 104,such as a packer 110. Alternately, or additionally, optical fiber 128can be functionally coupled to optical fiber 126 inside a protectivetube, such as inside a hydraulic line. Protective tubes can include anytubes or lines known in the art, including for example, sheaths, armoredlines, sprayed on coatings, quarter inch diameter lines, one eight inchdiameter lines, etc. Moreover, the protective tubes can be formed fromany materials known in the art, including, for example, stainless steel,sapphire, etc.

When a protective tube is used, in one possible aspect, once opticalfiber 126 and optical fiber 128 are functionally coupled using opticalfiber connectors 129 and 131, cleaning fluid can be pumped through theprotective tube to clean faces and/or lenses at a point of interactionwhere optical signals are passed between optical fibers 126, 128 (suchas, for example, at the ends of optical fiber 126 and optical fiber128). In one possible implementation, the cleaning fluid can, forexample, wash away contaminants such as oil, dirt, etc., on faces and/orlenses of optical fiber 126 and optical fiber 128. Cleaning in thisfashion can decrease or eliminate optic scattering and other potentiallosses. In some such instances, some of the refraction matched cleaningfluid can remain in place during conveyance of information betweenoptical fiber 126 and optical fiber 128. In one possible aspect, thecleaning fluid can comprise a refraction matched fluid opticallycompatible with optical fiber 126, optical fiber 128 and/or any lensesthat might be positioned there between.

In one possible implementation, optical fiber 126 and optical fiber 128,and the protective tube surrounding them, can be shop assembled. Forinstance, the protective tube can be filled with oil and pressurebalanced with a hermetic, glass-sealing of optic fibers 126, 128. In onepossible embodiment, optic fibers 126, 128 can be single channel, with amechanical housing system to handle debris management.

Further details regarding optical fiber connectors 129 and 131 are shownin FIGS. 7A and 7B and described in the accompanying description.

FIG. 2 illustrates an example latch 200 coupling upper element 102 andlower element 104. As illustrated, latch 200 secures upper element 102to lower element 104 via an alignment key 202 on upper element 102 whichfits in an associated keyway 204 on lower element 104. The contourededge 205 of the lower completion 104 guides the alignment key 202 intothe keyway 204 when the upper element 102 and lower element 104 arerotationally misaligned. In one possible implementation, the tolerancebetween the alignment key 202 and the keyway 204 can determine how muchupper element 102 and lower element 104 are able to rotate relative toone another. Moreover, in another possible implementation, the length ofalignment key 202 and keyway 204 can be used to lessen or eliminateangular misalignment between upper element 102 and lower element 104(i.e. function as an alignment latch). Stated another way for the sakeof clarity, a longer alignment key 202 in a longer keyway 204 canincrease the likelihood that upper element 102 and lower element 104 liealong a common axis.

In one possible embodiment, a length of terminal end 114 seated withinreceiving end 116 of lower element 104 can perform a similarfunctionality as an alignment latch. For example, the longer the lengthof the terminal end 114 seated within receiving end 116, the greater thelikelihood that angular misalignment between the upper element 102 andthe lower element 104 will be avoided.

Latch 200 can also include additional functionality 206, such as lockinglatch functionality configured to resist rotation of upper element 102and lower element 104 relative to one another and/or sliding of upperelement 102 relative to lower element 104 along keyway 204 such thatupper element 102 and lower element 104 will not accidentally decoupleonce they have been coupled.

In addition to the alignment key 202 and keyway 204 configurationforming an alignment latch illustrated in FIG. 2, latch 200 can beconfigured in any other manner known in the art, and can use any varietyof functionalities to secure upper element 102 to lower element 104 andimprove alignment of upper element 102 and lower element 104. Thus,latch 200 can include anti-rotation functionality, anti-angularmisalignment functionality, anti-sliding functionality etc.Additionally, in one possible implementation, more than one latch 200may be employed on downhole assembly 100.

FIG. 2 shows optical fibers 126 and 128 and optical fiber connectors 129and 131. The optical fiber 126 and corresponding optical fiber connector131 are rigidly attached to lower element 104, while optical fiber 128and corresponding optical fiber connector 129 are rigidly attached tothe upper element 102. The use of latch 200 to couple upper element 102and lower element 104 can ensure that optical fiber connector 131(optical fiber 126) and optical fiber connector 129 (optical fiber 128)connect properly and that the elements remain in fixed alignment duringoperation of the completions. This alignment enables the face of opticalfiber connector 131 to communicate with a face of optical fiberconnector 129 so that optical signals can be successfully communicatedbetween the optical fibers 126, 128.

In addition to uses associated with downhole elements in a wellenvironment, such as those described in FIGS. 1A, 1B, and 2, it willalso be understood that the principles of optical fiber connection canbe used in any other environments (and with any equipment) found inoilfield services, including, for example, surface environments, seabedenvironments, etc.

For instance, the principles of optical fiber connection as describedherein can be used to couple optical fibers (such as optical fibers 126,128) anywhere as desired in a subsea system, including, for example, invertical and/or horizontal subsea trees, surface junction boxes, anypoints where an optical fiber has a splice break surface, etc.

In another possible implementation, the optical fiber connection asdescribed herein can be used to couple optical fibers at and/or in awellhead outlet, in a hybrid cable (with, for example, electrical andoptical fibers).

Examples of Mode Conversion

Several difficulties can arise when attempting to align optical fiber126 to communicate with optical fiber 128. For example, when one or moreof optical fibers 126, 128 include a fragile end face, contact betweenoptical fibers 126, 128 can scratch or otherwise degrade the fragileface(s), resulting in a reduced efficiency of transmission of opticalsignals between optical fibers 126, 128.

One possible solution for such a difficulty can include the utilizationof a contactless coupling of optical fibers 126, 128 (examples of whichwill be described in more detail below). Another possible solution caninclude the employment of robust end pieces on optical fibers 126, 128made from crush and/or scratch resistant materials such as, for example,sapphire or diamond.

Another difficulty associated with attempting to align optical fibers126, 128 can arise when small diameter optical fiber cores are used,such as single mode optical fibers. Such fibers may have optical signaltransmitting cores with diameters in the range of a few micrometers. Atypical optical fiber has a core diameter of 8 microns. A typicaldiameter (with cladding) for an optical fiber is 250 microns. On a scaleas small as this, misalignment of end faces of optical fiber cores by aslittle as a few tens of nano-meters can reduce or destroy couplingefficiency of optical fibers 126, 128.

This issue can be addressed by converting the mode of the optical signalwithin a first optical fiber core to a larger second mode. For example,in one embodiment, the mode size is increased by increasing the corediameter of the small diameter optical fiber core to a larger corediameter (such as that of a large area core optical fiber) using one ormore mode converters. In one possible implementation, the mode convertercan increase the diameter of the small optical fiber core as large as isdesired to facilitate alignment and/or communication between opticalfibers 126, 128. For example, in one possible implementation the modeconverter can increase the diameter of the small diameter optical fibercore to a diameter between one eighth of an inch (0.3175 cm) to onequarter of an inch (0.635 cm). In another possible implementation, themode converter can increase the diameter of the small diameter opticalfiber core to a diameter equal to or greater than one quarter inch(0.635 cm). In yet another possible implementation, the mode convertercan increase the diameter of the small diameter optical fiber core to adiameter less than one eighth of an inch (0.3175 cm).

The “mode” of the optical signal is the form that an optical signal willtake as the signal propagates through a medium. The form of the opticalsignal can be determined using the Helmholtz equation. The mode of anoptical signal can be enlarged by increasing the size of the form. Forexample, the LPO1 mode of an optical signal within an optical fiber coreproduced a circular form. The LPO1 mode can be enlarged by increasingthe diameter of the circular form. In this manner, the form of the moderemains constant, but the size of the mode is enlarged.

FIG. 3 illustrates an example mode converter design 300 configured toconnect optical fibers 126, 128. As shown, a mode converter 402increases a diameter of single mode optical fiber core 401 to a diameterof a larger diameter optical fiber core 404. Mode converter 402 doesthis by gradually tapering down the diameter of single mode opticalfiber core 401 along a taper 406 inside a length of the mode converter402. By tapering, and through use of mode converter 402, the diameter ofoptical fiber core 401 is gradually converted to match that of largediameter optical fiber core 404.

In various embodiments, a second mode converter 402(2) can increase adiameter of single mode optical fiber core 401(2) to a diameter of asecond larger diameter optical fiber core 404(2) configured to interfacewith large diameter optical fiber 404. The second mode converter 402(2)does this by gradually tapering down the diameter of single mode opticalfiber core 401(2) along a second taper 406(2) inside a length of thesecond mode converter 402(2), which overlaps with large diameter opticalfiber core 404(2).

Cladding 405 for the optical fibers 126, 128 is shown in FIG. 3, but isomitted from FIGS. 4-9 for the sake of simplicity. Cladding 405 may alsobe provided on the large diameter optical fiber cores 404, 404(2) and/orthe mode converters 402, 402(2).

FIG. 4 shows another mode converter design 400. As illustrated in thisexample configuration, mode converter 402 can be used to increase adiameter of single mode optical fiber core 401 to match a diameter oflarge diameter optical fiber core 404. In one possible embodiment, asecond mode converter 402(2) can be employed to similarly increase adiameter of single mode optical fiber core 401(2) to match a diameter oflarge diameter optical fiber core 404(2). Mode converters 402, 402(2)can increase the diameters of optical fiber cores 401, 401(2) asgradually or as a rapidly as desired to match the diameters of largediameter optical fiber cores 404(2), 404.

The diameters of large optical fiber cores 404, 404(2) in FIGS. 3 and 4can be chosen on a variety of bases, including ease of alignment,reliability of optical signal transmission and/or reception, etc. In onepossible aspect, diameters of large optical fiber cores 404, 404(2) canbe approximately equal.

In various embodiments, an anti-reflection coating can be added to thefaces 408, 408(2) of the large diameter optical fiber cores 404, 404(2)of FIGS. 3 and 4. In one possible aspect, this anti-reflection coatingcan reduce reflection of optical signals from faces 408, 408(2) at apoint of interaction 410. Any anti-reflection coating known in the artcan be used, such as silicon dioxide and titanium dioxide.

Moreover, both contact and contactless connections can be completedbetween the large diameter optical fiber cores 404, 404(2) of FIGS. 3and 4. When the connection is contactless, fluid can be placed betweenlarge diameter fiber core 404 and large diameter optical fiber core404(2). The fluid can be chosen to match a refraction index of the largediameter optical fiber cores 404, 404(2).

FIG. 5 shows another example mode converter design 500 configured totransfer an optical mode from a small diameter single mode optical fibercore to large diameter optical fiber core. In one possibleimplementation, this design can be contactless, utilizing a graded indexlens 502. Mode converter 402 can be used to transfer the optical modefrom small diameter single mode optical fiber core 401 to large diameteroptical fiber core 404. Using mode converter 402, the diameter of singlemode optical fiber core 401 can be increased as gradually or as steeplyas desired to match the diameter of large diameter optical fiber core404. A graded index lens 502 can be incorporated at the end of largediameter fiber core 404 to collimate the optical field at the output oflarge diameter optical fiber core.

In various embodiments, a design of a receiving fiber core can besymmetric. A second mode converter 402(2) can increase a diameter ofoptical fiber core 401(2) to a diameter of a second large diameteroptical fiber core 404(2). A second graded index lens 502(2) can then beincorporated at the end of the second large diameter fiber core tocollimate the optical field at the output of the second large diameteroptical fiber.

In one possible implementation, when graded index lenses (such as gradedindex lens 502, 502(2)) are used to collimate output fields, a gap canexist between face 408, face 408(2). In one possible aspect, this gapcan be at least partially filled with fluid, such as, for example, arefraction matched fluid. To reduce reflection of optical signals fromfaces 408 and 408(2), an anti-reflection coating can be added to one orboth faces. In a further embodiment, the mode converters 402, 402(2),the large diameter optical fiber cores 404, 404(2), and/or the gradedindex lenses 502, 502(2) can be made from the same material as the smallsingle mode fiber cores 401, 401(2).

FIG. 6 illustrates yet another example connection design 600 forconnecting optical fibers 126, 128. This design 600 uses lenses to forma mode converter. As shown in FIG. 6, a mode converter 402 is formedusing two lenses 602 and 602(2). The first lens 602 receive an expandinginput beam from the small optical fiber core 401. The first lens 602focuses this expanding input beam on a focal point between the first andsecond lenses. The second lens 602(2) receives the resulting beam andgenerates a collimated output beam 606 with a diameter that is largerthan the diameter of the small optical fiber core 401. The collimatedoutput beam 606 can be received by a second mode converter 402(2) withtwo lenses 602(3) and 602(4). The third lens 602(3) receives thecollimated output beam 606 and focuses the beam on a focal point betweenthe third and fourth lenses. The fourth lens 602(4) focuses theresulting beam onto a small optical fiber core 401(2).

By collimating output signal 606, alignment issues can be at leastpartially mitigated and also a gap 610 (with various different lengths)can be maintained and used between the lenses 602(2), 602(3), such thatthe lenses do not physically contact one another. In one possibleimplementation, gap 610 is filled with a fluid. This fluid can have arefraction index matching one or more of the lenses 602-602(4) and/orthe optical fiber cores 401, 401(2).

In various embodiments, the lenses 602-602(4) are aspheric lenses formedfrom a sapphire or diamond material. A solid matrix material 608, suchas glass, can be used to set the lenses and the optical fibers in placeand to provide structural integrity to the mode converters 402 and402(2).

The mode converters described herein can have a monolithic design or canbe fabricated from a collection of parts and materials. In FIG. 4, themode converters have a monolithic design (e.g. each mode converter isfabricated from a single material). In yet further embodiments, the modeconverter, the small optical fiber cores, and/or the large optical fibercores can be a single monolithic component. Alternatively, the modeconverters can be made from a collection of several parts. For example,FIG. 6 shows mode converters that each include two lenses. In someembodiments, the mode converters are formed into a solid component. Asused herein, the term “solid component” means a component that is formedentirely from solid materials. For example, the mode converters 402 and402(2) in FIG. 6 are solid components because they include a solidmatrix material that is used to set solid lenses in position and toprovide structural integrity to the mode converters. In yet furtherembodiments, the mode converter, the small optical fiber cores, and/orthe large optical fiber cores can be a single solid component. In otherembodiments, the mode converters do not have a solid component design.For example, in some embodiments, a fluid is located between the lenses.The fluid can be used to pressure compensate the mode converter and/orcan be chosen to match the refraction indexes of the lenses. Downholeconditions may expose the mode converters to high pressures, hightemperatures, corrosive environments, and/or mechanical shocks. Invarious embodiments, monolithic designs or solid component designs willhelp the mode converters perform more robustly and reliably underdownhole conditions.

FIGS. 7A and 7B show one example of an optical fiber connection 700.FIG. 7A shows a male fiber optical connector 702 and a female fiberoptical connector 704 when the elements are disconnected, while FIG. 7Bshows the elements when they are connected. The male fiber opticalconnector 702 includes a fiber assembly 706 (e.g., small diameter fibercore 401, a mode converter 402, and a large diameter fiber core 404).The fiber assembly 706 is contained in a housing 708 (e.g., protectivetube) that is filled with a fluid 710. The fluid can be used tocompensate for pressure outside of the housing and/or to match therefractive index of one or more components of the fiber assembly 706.Such refractive index matching fluids can be obtained from CargilleLaboratories of Cedar Grove, N.J. The male fiber optical connector 702further includes an isolation valve 712 at an end of the housing 708. Inthis embodiment, the isolation valve is a ball valve that includes aslot 714. The slot 714 is sized so that the fiber assembly 706 can fitthrough the slot.

The female fiber optical connector 704 includes a second fiber assembly716 (e.g., small diameter fiber core 401(2), a mode converter 402(2),and a large diameter fiber core 404(2)). The second fiber assembly 716is contained in a second housing 718 (e.g., protective tube) that isfilled with the fluid 710, which may also be used for pressurecompensation and/or as a refractive index matching fluid. The femaleconnector 704 includes a membrane 720 at the end of the second housing718. The material and the thickness of the membrane 720 are selected sothat the membrane maintains its integrity when the female connector isdisconnected, but so that the membrane ruptures when the connection ismade to the male connector 702. The membrane 720 can be made frommetallic or polymeric materials. The female connector 704 furtherincludes a fluid compensating piston 722 which adjusts to facilitatefluid 710 movement between the connectors 702 and 704 when a connectionis made.

FIG. 7B shows the elements 702 and 704 in a connected state. In order tomake the connection, the ball valve 714 engages the second housing 718of the female connector 704 and ruptures the membrane 720. As the ballvalve 712 engages the second housing 718, the ball valve is rotated byan axial lever 724. The slot 714 within the ball valve 714 is rotated tocreate fluid communication between the housing 708 and the secondhousing 718. The fiber assembly 706 is pushed through the slot 114 andoptically engages the second fiber assembly, thereby creating an opticalconnection between the two optical fibers 128, 126. In variousembodiments, the elements 702, 704 also create a seal between an innervolume within the housings (708 and 718) and an environment exterior tothe housings when the elements are in the connected state. This seal (i)prevents fluid 710 from escaping the inner volume and (ii) preventsdebris and other fluid from the exterior environment from entering theinner volume and affecting the transmission of optical signals betweenoptical fiber assemblies 706, 716.

The optical fiber connectors 702, 704 shown in FIGS. 7A and 7B can beused as the optical fiber connectors 129, 131 shown in FIGS. 1A, 1B, and2. The male connector 702 can be rigidly attached to the upper element102 and the female connector 704 can be rigidly attached to the lowerelement 104 (or vice versa). Various modifications can be made to theoptical fiber connectors and various other connection technologies canbe used. For example, the ball valve 712 can be removed and the fiberassembly 706 can protrude beyond the housing 708 so that the fiberassembly engages the second housing 718 and ruptures the membrane 720.

FIG. 8A shows a connector design that uses a beam forming grating. Inthis example configuration, a mode converter 402 can be used to transferthe optical mode from small diameter single mode optical fiber core 401to large diameter optical fiber core 404. Large diameter optical fibercore 404 includes a beam forming fiber grating 802 which can take anoptical signal from the optical fiber core 404 and create a collimatedbeam in the far field so that the optical signal is transmitted to acorresponding grating. The beam forming fiber grating 802 can performperiodic refractive index modulation at individual elements 804. In onepossible implementation, individual elements 804 in beam forming fibergrating 802 can scatter the optical signal from optical fiber core 404at a point of interaction 410 and form a coherent superposition in thefar field.

In one possible embodiment, mode converter design 800 can be aside-coupled design with a gap 806 between large diameter optical fibercore 404 and large diameter optical fiber core 404(2). In one possibleimplementation, this contactless solution can have a tolerance tomisalignment along and across the axis of large diameter optical fibercore 404 and large diameter optical fiber core 404(2). In one possibleimplementation, gap 806 can be large enough to allow beam reforming fromeach element 804 in receiving elements 808 on opposing large diameteroptical fiber core 404(2). In one possible aspect, gap 806 can be filledat least partially with a fluid. In one possible aspect, this fluid canhave a refraction index matching one or both of large diameter opticalfiber core 404 and core 404(2).

FIG. 8B shows a connector design that uses a beam forming grating with acurved shape. The beam forming grating 802 and the large fiber core 404form a curved (e.g., ringed) shape and are affixed to an inner surface818 of a tube (or mandrel) 816 on a plane that is perpendicular to theaxis of the tube. In a similar manner, the beam forming grating 802 canalso be affixed to the terminal end of a well completion element. Whencoupled to a corresponding well completion element with receivingelements 808 affixed in similar manner, the beam forming grating 802 canestablish optical communication. In various embodiments, suchconfigurations have greater tolerance for rotational misalignmentbetween completion elements. Other configurations are also possible. Forexample, the beam forming grating 802 can be affixed to an outer surface820 of the tube 816 and/or may be affixed in a direction perpendicularto the axis of the tube.

FIG. 9 shows a connector design that uses a resonant beam forminggrating. In this example configuration, mode converter 402 can be usedto increase the diameter of single mode optical fiber core 401 to matcha diameter of the large diameter fiber core 404. A resonant beam formingfiber grating 902 on large diameter fiber core 404 can create acollimated beam in the far field from an optical signal received fromoptical fiber core 401. In one possible implementation, beam forminggrating 902 can effect periodic refractive index modulation on anoptical signal received from optical fiber core 401 via individualelements 904. Individual elements 904 can scatter the optical signalreceived from optical fiber core 401, forming a coherent superpositionin the far field. In one possible implementation, mode converter design900 can be a side-coupled design with a gap 906 existing at point ofinteraction 410 between large diameter fiber core 404 and large diameterfiber core 404(2).

In one possible embodiment, the design 900 can be contactless, with atolerance to misalignment along and across an axis of large diameteroptical fiber core 404 and large diameter optical fiber core 404(2). Inone possible aspect, the gap 906 can be large enough to allow beamreforming from each element 904 in corresponding elements 908 onopposing large diameter optical fiber core 404(2) to be opticallyconnected to single mode optical fiber core 401(2). In one possibleaspect, gap 906 can be filled at least partially with a fluid. In onepossible aspect, this fluid can have a refraction index matching one ormore of large diameter optical fiber cores 404 and 404(2).

It will be understood that the mode converters 402, 402(2) as describedherein can be constructed from any materials known in the art, includingplastic, glass, sapphire, etc. This includes constructing modeconverters 402, 402(2) out of the same materials as the optical fibercores 401, 401(2)

Also, in one possible implementation, mode converters 402, 402(2) mayinclude their respective large diameter optical fiber core 404, 404(2)and/or the respective large diameter optical fiber cores can be a partof the mode converters. Furthermore, the mode converters 402, 402(2) andtheir respective large diameter optical fiber core 404, 404(2) can forma single solid component and/or a single monolithic component.

Additionally, it will be understood that communications of opticalsignals associated with the various embodiments described herein may befacilitated in either direction between optical fiber 126 and opticalfiber 128.

Example Methods

FIG. 10 illustrates an example method for implementing aspects ofoptical fiber connection. The methods are illustrated as a collection ofblocks and other elements in a logical flow graph representing asequence of operations. For purposes of illustration, and not purposesof limitation, selected aspects of the methods may be described withreference to elements shown in FIGS. 1-9.

FIG. 10 illustrates an example method 1000 associated with embodimentsof optical fiber connection. At block 1002 an optical signal is receivedat a small diameter optical fiber core. For example, an optical signalcan be received at optical fiber 126 from a sensor 124. In one possibleimplementation, the diameter of the small diameter optic fiber core issmall enough to complicate alignment and coupling of the small diameteroptic fiber core with another similarly small diameter optic fiber core.

At block 1004, the optical signal is transmitted through a modeconverter to a larger diameter optical fiber core. For example theoptical signal is transmitted though mode converter 402(2) to largediameter optic fiber core 404(2). The mode converter can increase thediameter of the small optical fiber core to the diameter of the largerdiameter optical fiber core as gradually or rapidly as desired. Moreoverthe diameter of the large diameter optical fiber core can be chosen on avariety of bases, including ease of alignment of the large diameteroptical fiber core with another large diameter optical fiber core (suchas large diameter optical fiber core 404), reliability of optical signaltransmission from the large diameter optical fiber core and/or receptionat the large diameter optical fiber core, etc.

Example Computing Systems

FIG. 11 illustrates an example system 1100, such as one or morecomputing devices, programmable logic controllers (PLCs), etc., with aprocessor 1102 and memory 1104 for hosting an optical fiber connectionmodule 1106 for implementing various embodiments of fiber opticconnection as discussed in this disclosure (including, for example,issuing commands to generate and/or send optical signals, receivingoptical signals, analyzing optical signals to receive data and/ormeasurements associated therewith, etc.). System 1100 is one example ofa computing device or programmable device, and is not intended tosuggest any limitation as to scope of use or functionality of system1100 and/or its possible architectures. Further, system 1100 should notbe interpreted as having any dependency relating to one or a combinationof components illustrated in the system 1100. For example, system 1100may include a computer, such as a laptop computer, a desktop computer, amainframe computer, a sensing device, etc., or any combination oraccumulation thereof.

In one possible implementation, system 1100 includes one or moreprocessors or processing units 1102, one or more memory components 1104(on which, for example, fiber optic connection module 1106 may be storedin whole or in part), a bus 1108 configured to allow various componentsand devices to communicate with each other, and local data storage 1110,among other components.

Memory 1104 may include one or more forms of volatile data storage mediasuch as random access memory (RAM)), and/or one or more forms ofnonvolatile storage media (such as read-only memory (ROM), flash memory,and so forth).

Bus 1108 can include one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. Bus 1108 can also include wiredand/or wireless buses.

Local data storage 1110 can include fixed media (e.g., RAM, ROM, a fixedhard drive, etc.) as well as removable media (e.g., a flash memorydrive, a removable hard drive, optical disks, magnetic disks, and soforth).

One or more input/output (I/O) device(s) 1112 may also communicate via auser interface (UI) controller 1114, which may connect with the I/Odevice(s) 1112 either directly or through bus 1108.

In one possible implementation, a network interface 1116 may communicateoutside of system 1100 via a connected network, and in someimplementations may communicate with hardware.

In one possible embodiment, users and devices may communicate withsystem 1100 via input/output devices 1112 via bus 1108. In one possibleimplementation, input/output devices 1112 can include various devicescapable of sending and/or receiving optical signals and/or convertingbetween optical signals and digital information suitable for use bysystem 1100.

A media drive/interface 1118 can accept removable tangible media 1120,such as flash drives, optical disks, removable hard drives, softwareproducts, etc. In one possible implementation, logic, computinginstructions, and/or software program comprising elements of the fiberoptic connection module 1106 may reside on removable media 1120 readableby media drive/interface 1118.

In one possible embodiment, one or more input/output devices 1112 canallow a user to enter commands and information to system 1100, and alsoallow information to be presented to the user and/or other components ordevices. Examples of input devices 1120 include, in someimplementations, sensors, a keyboard, a cursor control device (e.g., amouse), a microphone, a scanner, and any other input devices known inthe art. Examples of output devices include a display device (e.g., amonitor or projector), speakers, a printer, a network card, and so on.

Various processes of fiber optic connection module 1106 may be describedherein in the general context of software or program modules, or thetechniques and modules may be implemented in pure computing hardware.Software generally includes routines, programs, objects, components,data structures, and so forth that perform particular tasks or implementparticular abstract data types. An implementation of these modules andtechniques may be stored on or transmitted across some form of tangiblecomputer-readable media. Computer-readable media can be any availabledata storage medium or media that is tangible and can be accessed by acomputing device. Computer readable media may thus comprise computerstorage media.

“Computer storage media” designates tangible media, and includesvolatile and non-volatile, removable and non-removable tangible mediaimplemented for storage of information such as computer readableinstructions, data structures, program modules, or other data. Computerstorage media include, but are not limited to, RAM, ROM, EEPROM, flashmemory or other memory technology, CD-ROM, digital versatile disks (DVD)or other optical storage, magnetic cassettes, magnetic tape, magneticdisk storage or other magnetic storage devices, or any other tangiblemedium which can be used to store the desired information, and which canbe accessed by a computer.

Some examples discussed herein involve technologies from the oilfieldservices industry. It will be understood however that the techniques ofoptical fiber connection described herein can be used in a wide range ofindustries outside of the oilfield services sector, including anyindustries where fiber optic technology is used continuously and/orintermittently to convey things such as data, measurements, power (suchas optical power), etc. This includes industries that, for example,utilize connections between large-scale microphotonic sensing andimaging arrays, etc.

Although a few example embodiments have been described in detail above,those skilled in the art will readily appreciate that many modificationsare possible in the example embodiments without materially departingfrom this disclosure. Accordingly, such modifications are intended to beincluded within the scope of this disclosure as defined in the followingclaims. Moreover, embodiments may be performed in the absence of anycomponent not explicitly described herein.

1. A downhole assembly comprising: a first well completion elementcomprising: an end that is configured to couple with a correspondingsecond well completion element; an optical fiber that extends along atleast a portion of the first well completion element and is configuredto transmit an optical signal using a first mode; and a mode converterconfigured to receive the optical signal from the optical fiber andconvert the optical signal from the first mode to a second larger mode.2. The downhole assembly of claim 1, further comprising a graded indexlens configured to collimate an optical field at an output of the secondlarger mode.
 3. The downhole assembly of claim 1, wherein the modeconverter transmits the optical signal to a second optical fiber thattransmits the optical signal using the second larger mode.
 4. Thedownhole assembly of claim 3, wherein the optical fiber comprises afirst core having a first diameter, the second optical fiber comprises asecond core having a second diameter, and the second diameter is largerthan the first diameter.
 5. The downhole assembly of claim 1, whereinthe first well completion element further comprises: an optical fiberconnector that is (i) affixed to the end of the first well completionelement, (ii) coupled to the optical fiber, and (iii) comprises the modeconverter, wherein the optical fiber connector is configured to connectto a corresponding optical fiber connector affixed to the second wellcompletion element.
 6. The downhole assembly of claim 5, wherein theoptical fiber connector comprises a housing that contains the modeconverter, the optical fiber sensor, and a fluid.
 7. The downholeassembly of claim 6, wherein the optical fiber connector furthercomprises a valve located at an end of the housing.
 8. The downholeassembly of claim 6, wherein the optical fiber connector furthercomprises a membrane located at an end of the housing.
 9. The downholeassembly of claim 6, wherein the first well completion element comprisesa pump configured to deliver cleaning fluid inside the housing to themode converter.
 10. The downhole assembly of claim 1, wherein the firstwell completion element comprises a latch for securing the first wellcompletion element to the second well completion element.
 11. Thedownhole assembly of claim 1, wherein the first well completion elementcomprises at least one of: an alignment key for guiding a couplingoperation between the first well completion element and the second wellcompletion element; and a keyway for guiding a coupling operationbetween the first well completion element and the second well completionelement.
 12. The downhole assembly of claim 1, wherein the optical fibercomprises a single mode optical fiber.
 13. The downhole assembly ofclaim 1, wherein the mode converter comprises two or more lenses thatare not in physical contact with each another.
 14. The downhole assemblyof claim 1, wherein the mode converter comprises an anti-reflectivecoating.
 15. The downhole assembly of claim 1, wherein the modeconverter is monolithic.
 16. A downhole assembly comprising: a firstwell completion element comprising: a first end that is configured tocouple with a second end of a second well completion element; a firstoptical fiber sensor that extends along at least a portion the firstwell completion element and is configured to transmit an optical signalusing a first mode; and a first optical fiber connector that is (i)affixed to the first end of the first well completion element, (ii)coupled to the first optical fiber sensor, (iii) comprises a first modeconverter configured to receive the optical signal from the firstoptical fiber sensor and convert the optical signal from the first modeto a second larger mode, and (iv) comprises a graded index lensconfigured to collimate an optical field at an output of the secondlarger mode; and the second well completion element comprising: thesecond end that is configured to couple with the first end of the firstwell completion element; a second optical fiber sensor that extendsalong at least a portion the second well completion element and isconfigured to transmit the optical signal using the first mode; and asecond optical fiber connector that is (i) affixed to the second end ofthe second well completion element, (ii) coupled to the second opticalfiber sensor, and (iii) comprises a second mode converter configured toconvert the optical signal from the second larger mode to the first modeand transmit the optical signal to the second optical fiber sensor;wherein the first optical fiber connector is configured to opticallycouple to the second optical fiber connector.
 17. An optical fiberconnector comprising: an optical fiber sensor configured to transmit anoptical signal using a first mode; and a mode converter configured toreceive the optical signal from the optical fiber sensor and convert theoptical signal from a first mode to a second larger mode; wherein themode converter and at least a portion of the optical fiber are a singlesolid component.
 18. The optical fiber connector of claim 17, furthercomprising a graded index lens configured to collimate an optical fieldat an output of the second larger mode.
 19. The optical fiber connectorof claim 17, wherein the connector is configured to make a contactlessconnection with a corresponding optical fiber connector.
 20. The opticalfiber connector of claim 17, wherein the mode converter is configured totransmit the optical signal through a fluid and to a correspondingoptical fiber connector.